I. Field of the Invention
The present invention relates generally to bus plugs.
II. Description of Related Art
Modern day factories are typically equipped with electrical bus for supplying three phase electrical power to the machinery in the factory. The electrical bus typically includes three main conductors and occasionally has a neutral phase and an integral ground bar. The supply voltage may be either 240 or with 600 volts being the maximum rating.
In order to electrically connect the electrical bus with the machinery, conventionally a bus plug is attached to the preexisting ports along a length of bus. The bus plug contains three fuses, one for each phase bar of the electrical bus. Consequently, once the bus plug is attached to the electrical bus, one end of each of the electrical fuses is electrically connected to the electrical bus (line side). The other ends of the fuses (load side) are then connected to the machinery which is powered through the electrical bus plug.
Electrical equipment of the type used in factories is typically powered by either 240 or 480 volts. Conventionally, an N class bus plug is employed with a 240 volt electrical bus and N class fuses are conventionally used with the N class bus plug. Such N class fuses are rated to operate at 240 volts.
Conversely, an R class bus plug is conventionally employed with electrical buses maintained at 480 volts. Such R class bus plugs accept R class fuses which are rated at 600 volts maximum. Such R class fuses are significantly longer than the N class fuses utilized in the 240 volt bus plug.
Since the R class fuses for 600 volts are longer in size than the N class fuses for 240 volts, the housing for an R class bus plug is also longer in size than the N class bus plug. This, in turn, increases the overall cost of an R class bus plug. Furthermore, R class bus plugs are much rarer than the N class bus plugs and thus more costly to obtain for the reconditioning and refurbishing business for such bus plugs.
There is a J class fuse which is essentially the same in size as the N class fuse, but the J class fuse is rated up to 600 volts. It is not possible, however, to simply replace the N class fuse in an N class bus plug with a J class fuse since the J class fuse uses a different electrical connection than the N class fuse. Consequently, where a 600 volt bus plug has been required, it has been necessary previously to use the larger size and more expensive R class bus plug with its larger housing.